class List extends React.Component{
    doNow: List.doNow;
    constructor(props){
        super(props);
        this.doNow=function(){
            console.log("构造函数执行了");
        }
        this.state = {
            listT:[[1,2,3],[4,5,6,7],[8,9,0]]
        }
    }
    componentDidMount(){
        console.log("组件挂载成功");
    }
    render(){
        const listItems = this.state.listT.map((item)=>{
           const cc = item.map((i,index)=><li key = {index.toString()}>{i}</li>)
            //console.log(cc)
            return cc;
        })
        //console.log(listItems)
        return (
            <div>
                我已经加载了为何不显示
                <ul>
                    {listItems}
                </ul>
            </div>
        )
    }
}